Resins organic compounds from water

The XAD-4 quaternary resin used in these studies was prepared by the Ames Laboratory in Ames, Iowa. This resin had been used in studies by the Ames group for the adsorption and selective separation of acidic material in waste waters. For this study, the resin was chosen for its effectiveness in concentrating anionic material from solution. At the same time, it was thought that sufficient sites would be available to effectively adsorb neutral organic compounds from water. The resin was basically an XAD-4 macroreticular cross-linked polystyrene into which a trimethylamine group was introduced. The resin was stored in the chloride form but was converted to the hydroxide form before use in the resin sorption experiments. 

In more recent work the same group immobilized j8-cyclodextrin (CD) on solid support [27]. Initially 1,6-hexamethylene diisocyanate (HMDI) was quantitatively introduced as a linker to conventional PEGylated Merrifield resin (PS-PEG). fi-CD was subsequently attached to the prepared PS-PEG-HMDI polymer by microwave irradiation at 70 °C for 30 min (Scheme 16.4a). The resulting jS-CD resins are insoluble in water and can be used to trap volatile organic compounds from water. 

A column filled with sorbent material, through which an aqueous sample is passed, provides another means of isolating certain organic compounds from water 96-298) The adsorbent materials used are varied activated carbon, XAD resins, Tenax-GC, bonded organic phases on silica and polyurethane foam to name a few . 

Resins such as phenol formaldehyde and highly sulphonated styrene/divinyl benzene macroporous ion exchange resins can be pyrolysed to produce carbonaceous adsorbents which have macro-, meso- and microporosity. Surface areas may range up to 1100 m /g. These adsorbents tend to be more hydrophobic than granular activated carbon and therefore one important application is the removal of organic compounds from water. 

Macroreticular resins, particularly the Amberlite XAD series, have been used extensively to isolate and concentrate trace organic compounds from drinking water (1-8). We have previously reported the use of an XAD cartridge for this purpose and have evaluated the system for the analysis of organophosphorus pesticides (OPs) (4), polynuclear aromatic hydrocarbons (PAHs) (5), phosphate triesters (TAAPs) (6), or-... 

The handling and disposal problems associated with the use of liquid solvent extractors have resulted in increased attention to the separation and preconcentration of organic compounds in water by collection in synthetic polymers followed by elution with an organic solvent (2). For example, selective collection and concentration of organic bases on methylacrylic ester resin from dilute water samples have been reported (3). Such collection techniques are especially well-suited to flow-injection measurement techniques. In this study, ionizable organic analytes such as salicylic acid and 8-hydroxyquinoline (oxine) were extracted into a polymer and then back extracted by an aqueous solution. Amperometric measurement using a flow-injection technique was employed to monitor the process. 

Duarte, R. M. B. O., and Duarte, A. C. (2005). Application of non-ionic solid sorbents (XAD resins) for the isolation and fractionation of water-soluble organic compounds from atmospheric aerosols. J. Atmos. Chem. 51,79-93. 

A specific application of environmental SPE is sample preparation of extra-large volumes (from 10 to 100 L). This work was pioneered in the early 1970s by Junk and co-workers (1974) for the analysis of trace organic compounds in water using styrene-divinylbenzene copolymers (XAD-2 resin from Rohm and Haas) and by Thurman and Malcolm (1981) and Leenheer and Stuber (1981) for the analysis of natural organic substances in water (humic substances). One can obtain the XAD resins from Supelco (Appendix Products Guide) and still follow the protocol of this early work for the isolation of contaminants and humic substances from large volumes of water (10-1000 L of water). 

Part 111 describes in detail the use of hypercrosshnked sorbents, both industrial resins and laboratory-made polymers, for the sorption of organic compounds from air, water, and biological liquids and for the pre-concentration of analytes in SPE, as well as the use of hypercrosshnked resins as matrices for ion-exchange resins and as separating media in gas and hquid chromatography. 

The surfaces of the resins are highly aromatic. Sizable fractions of the surfaces are benzene rings (Albright, 1986). For this reason, the unfunctionalized polymeric resins are hydrophobic. The ion exchange resins are, however, not hydrophobic. The hydrophobic resins need to be pretreated to become wetted prior to use in water treatment. The pretreatment involves immersion in a water-soluble solvent, such as acetone or methanol, to displace air from the pores, followed by displacement of the solvent by water or aqueous solution. The aromatic surfaces of the resins make them excellent sorbents for removal of organic compounds from aqueous solution, particularly those with low solubilities. 

Polar organic compounds such as amino acids normally do not polymerize in water because of dipole-dipole interactions. However, polymerization of amino acids to peptides may occur on clay surfaces. For example, Degens and Metheja51 found kaolinite to serve as a catalyst for the polymerization of amino acids to peptides. In natural systems, Cu2+ is not very likely to exist in significant concentrations. However, Fe3+ may be present in the deep-well environment in sufficient amounts to enhance the adsorption of phenol, benzene, and related aromatics. Wastes from resinmanufacturing facilities, food-processing plants, pharmaceutical plants, and other types of chemical plants occasionally contain resin-like materials that may polymerize to form solids at deep-well-injection pressures and temperatures. 

Lac is derived from lac resin, the hardened secretion of the lac insect, the only known resin of animal origin. The lac insect, Kerria lacca, formerly known as Laccifer lacca, is a natural parasite of a variety of trees in large areas of southern Asia. Three different products are derived from lac resin lac dye, lac wax, and shellac. To obtain the lac resin, twigs encrusted with the secretion of the insects are cut down from the trees, then the incrustation is separated from the twigs, washed with water, and filtered. The wax and shellac, which are insoluble in water, remain as a solid residue of the filtration, while the soluble red dye (lac) is obtained as a powder when the water from the filtered solution is evaporated. The coloring matter in lac dye is an organic compound known as laccaic acid. 

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